This invention relates to devices for forming images of the inside of a pipe and particularly to a panoramic camera mounted on a cart that travels inside the pipe and transmits pictures to an above ground station.
Inspection and repair of pipe, particularly underground pipe, has a number of complications.
One complication is that a break in the pipe is often not discovered until the break has a been enlarged to the extent that a substantial amount of leakage/damage has occurred. A characteristic of the problem is that a only a small length of the pipe has deteriorated and the remaining length of the pipe is in good condition and has many years of life remaining. Therefore the use of devices for inspecting the interior of the pipe to detect the beginning of a break and determining its location have been disclosed as a way of conducting preventative maintenance and replacing short sections of pipe to prevent later more expensive incidents.
U.S. Pat. No. 3,557,674 to Carney discloses a small capsule that is fitted in pipes at least as mall as eight inches diameter. A Line has one end attache to the capsule and extends to a control station at an open end of the pipe for pulling the pipe through the pipe. The capsule holds a single frame 35 mm. camera mounted in a generally cylindrical capsule with a strobe light, electric drive motor with battery for advancing the frames of the film. A pair of wires connected the capsule to the control station for controlling the strobe light and frame advance. This arrangement requires that the pipe have two open accessible ends and at least a snake for positioning the rope inside the pipe.
U.S. Pat. No. 3,621,767, to Hyzer discloses a cylindrical housing containing a camera and mounted on a pair of runners. A tow rope has one end attached to a front end of the housing and extends to the forward opening of the pipe. A second rope has two ends accessible at the rearward opening of the pipe and a middle section of the second rope looped around a pulley wheel mounted on the rearward end of the housing. The device is moved through the pipe by pulling on the tow rope. Location of the device in the pipe for correlation with pictures taken with the camera is accomplished by correlating the length of the tow rope extending into the pipe. Slack in the tow rope that would introduce positioning errors is prevented by maintaining the second rope in a taut condition.
U.S. Pat. No. 5,754,220 to Smalser discloses a portable apparatus for inspecting interior of a pipe comprising a battery operated television camera connected to one end of a coaxial cable adapted to be stored on a rotatable storage drum. The camera is mounted in a cylindrical housing and is manually pushed into the cable.
All of the above disclosures require positioning a tow rope in the pipe which requires that the pipe have two open accessible ends. They are not adaptable, example to a situation where the pipe is very long or where there is a blockage in the pipe, a bend in the pipe or a collapsed section of pipe.
Another disadvantage of the cited art is that the devices are generally restricted to a narrow range of small pipe diameters, (less than eight inches). The limitation of small diameter occurs because the line of sight of the camera lens is at a fixed distance from the supporting area of the interior pipe surface
In addition to the problem of correlating the picture recorded to the position of the camera inside the pipe, there is additionally the problem imposed by the special condition imposed by the geometry of the pipe, i.e., producing an image that shows the entire circumferential band surface of a length of pipe.
In this regard U.S. Pat. No. 5,654,795 to Dierlam discloses a visual inspection apparatus for viewing welds between pipe sections. A TV camera is aimed along the centerline of the apparatus and pipeline and a mirror reflects the image of a portion of of the weld into the lens of the camera. The mirror can be rotated to allow the entire circumference of the weld to be inspected. The camera is connected by a cable to a video monitor and/or a VCR exterior to the pipe. The surface of the pipe is illuminated by a source of light transmitted through a light pipe.
U.S. Pat. No. 5,920,337 to Glassman et al discloses an omnidirectional visual image detector and processor (incorporation herein by reference). There is described a reflective rotund lens (either a cone or spherical section) which reflects the object beam from a surrounding view (encircling the lens) to a direction parallel to the axis of the rotund lens. The beam then passes through an objective lens and is focussed onto a CCD (charge coupled device) where image data is detected and processed for storage or image presentation on a monitor.
It is an object of this invention to provide a device and method for recording an image of the interior of a pipe at continuous locations along the length of the pipe even where the pipe is very long, or has a blockage such as a right angle bend or is otherwise inaccessible from both ends of the pipe.
It is another object that the image at each location be a view of the entire circumferential area of the interior surface.
It is another object that the image be presented to the operator in real time and will be seen on an analog TV monitor with a built in VCR to record real time data.
It is yet another object that the device be adaptable to us with pipe having a diameter that occurs in a large range of diameters, specifically from 6 inches to 30 inches.
This invention is directed toward a video camera that is mounted on a self powered cart In one embodiment, the cart is mounted on a pair of caterpillar treads that are particularly adaptable to rolling over some obstacles that would otherwise block movement of the cart.
In one embodiment, the camera is mounted on the forward end of the cart by a cantilever that is adjustable so that the line of sight of the camera is coincident with the centerline of the pipe for pipe that has a diameter falling in a range of diameters, (e.g., 8 inches to 30 inches). The cart is provided with a transmitter and antenna that transmits image data from the cart back to a receiver at the open end of the pipe. Control signals such as forward-backward, picture format, etc., can also be transmitted from a computer monitor at the open pipe end to the cart.
In another embodiment, the support of the camera on the cart is adapted to permit orientation of the central axis of a panoramic lens in a direction that is perpendicular to the motion of the cart.
In another embodiment, the support of the camera is adapted to orient the axis of the panoramic lens in any direction between vertical or perpendicular to the direction of motion of the cart.
These adaptations permit panoramic viewing of surroundings of the cart that is sent into otherwise inaccessible locations such as long passageways between collapsed walls or floors of buildings that have been subjected to earthquakes or fires.